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Chapter 7

Electrochemistry 11: Electrolytic Cells

ELECTROLYSIS
Galvanic cells convert chemical (potential) energy into electrical
(kinetic) energy, as described in Chapter 6. Electrolytic cells convert
electrical (kinetic) energy into chemical (potential) energy and there-
fore an electrolytic cell requires an external source of electrical energy,
such as a battery, for operation. For this reason, electrolysis can be
defined as the input of electrical energy from an external source, such
as a battery, as direct current to force a non-spontaneous reaction to
occur, i.e. AG + ve. The electrolyte is the solution, which can be either
an ionic or covalent compound that melts to produce ions or that
dissolves to give a solution that contains ions (charged species), such
as Na+ and Cl-. The electrode is the metalplate used to bring the
electrical energy to the solution, which then brings about the chemical
change in solution. Active electrodes are metals which have the same
element as that contained in the solution, i.e. the electrolyte. A typical
active electrode is copper. The copper is immersed in a solution of its
own ions, CU~+(~~). Znactive electrodes consist of a metal which does
not react with the solution in which it is immersed, but brings the
electrical energy to the solution. Platinum and graphite are examples
of inactive electrodes. Faraday 's Laws of Electrolysis are the governing
laws which form the background to electrolysis.